[Digestion] Heating of a digestor

[Davaa]

Dear AD listers,

We have built a 20 cubic metre digestor under ground in 2005/2006.
We have successfully used it for 2 families for summer of 2006. It was not
operational during winter 2006/2007 due to heating system. Now we are trying
to modify existing heating system.

100 m long heating pipe is installed under the floor. It was used for
heating from the beginning. Unfortunately it uses 5 kW boiler and pump the
water to underground.

It is quite expensive to use electrocity.

Please share your experience heating a digestor using a biogas/electric or
other system.

Brgds,
Davaa, Mongolia